Wastewater Surveillance

The SARS-CoV-2 and influenza viral load in wastewater is being tested at selected wastewater treatment plants (WWTP) in Germany as part of AMELAG (“Abwassermonitoring für die epidemiologische Lagebewertung”, German for wastewater monitoring for epidemiological situation assessment). In 2025, up to 70 wastewater treatment plants are to be sampled for SARS-CoV-2. The data collected will be integrated into this report in the coming weeks. For the calendar week 6 data from 61 WWTPs were available. Data from other WWTPs are provided continuously.

An assessment of the overall situation is conducted in conjunction with other indicators in the weekly report on acute respiratory diseases (ARE weekly report). A comparison between the aggregated SARS-CoV-2 viral load in wastewater and the COVID-19 incidence is shown in the weekly Grippeweb report.

The course of the viral loads aggregated across all sites is shown in Figure 1 in order to obtain an overall picture of the mean viral load and its development in Germany. Weekly mean values of the viral loads (given in gene copies / liter), previously transformed by the common logarithm, are computed, first for each site and then across all sites for the respective week. The mean values are weighted according to the number of inhabitants connected to the respective site. The estimation of the regression curve is also weighted, so that weekly mean values with higher uncertainty are given a lower weight in the estimation and vice versa. Recently, a slightly decreasing aggregated SARS-CoV-2 viral load can be observed. The development observed over the last few weeks may still change due to late notifications, especially from WWTPs with large population coverage.

Figure 1: Aggregated SARS-CoV-2 load in wastewater over time (grey dots) along with a regression curve (black line, estimated using the LOESS method) and associated 95% confidence intervals (light blue area). The change from the first to the second AMELAG phase, which was associated with a sharp decline in the number of participating treatment plants, is indicated by a vertical dashed line. The data was last updated on Tuesday the 11.02.2025, 10 am. The latest data used in the calculations is from the previous Wednesday’s sampling (05.02.2025, CW 6). Shown are 7-day averages, which refer to the period from Thursday to Wednesday; the most recent value is calculated from the data from 30.01.2025 (CW 5), to 05.02.2025 (CW 6). The date of the sample corresponds to the start date of the 24-hour composite sample.
The button on the right allows the display of the data points, regression curve and confidence intervals on the logarithmic scale or transformed back to the original scale. Changes in viral loads in the low value range are emphasized more strongly than values in the high value range on a logarithmic scale. By hovering over the individual points the calendar week, the date of the corresponding Wednesday, the viral load, the number of sites and the proportion of the total population that is included in the calculation at that time are shown.
Data for further sites are supplied subsequently.

The course of the viral load in wastewater is shown for the individual WWTPs in Figure 2.

Standort:

Figure 2: SARS-CoV-2 load in wastewater over time (grey dots) along with the regression curve (black line, estimated using the LOESS method) and associated 95% confidence intervals (light blue area). The individual measurements represent the average of the measured gene regions. If at least half of the measured gene regions are below the limit of quantification (LOQ), the measurement is considered as “< LOQ” (white dots). The data was last updated on 11.02.2025, 10 am. The date of the sample corresponds to the start date of the 24-hour composite sample.
The location can be selected using the filter. The button on the right allows you to display the data points, regression curve and confidence intervals on the logarithmic scale or transformed back to the original scale. Changes in viral loads in the low value range are emphasized more strongly than values in the high value range on a logarithmic scale. By hovering over the individual points the calendar week, date of sampling and viral load are shown.
Changes in laboratory or changes in the methods used in laboratories are indicated with a dashed, vertical line.
If fewer than 10 data points are available in total, before a minimum 4-week time window with no data or before or after a change of laboratory, only the individual data points are shown. The corresponding regression curves and confidence intervals will be calculated when at least 10 data points are available.
Data from other sites are supplied subsequently.

The SARS-CoV-2 and influenza viral load in wastewater is being tested at selected wastewater treatment plants (WWTP) in Germany as part of AMELAG (“Abwassermonitoring für die epidemiologische Lagebewertung”, German for wastewater monitoring for epidemiological situation assessment). In 2025, up to 70 wastewater treatment plants are to be sampled for influenza A virus and influenza B virus. The data collected will be integrated into this report in the coming weeks. For the calendar week 6 influenza A and B virus data from 52 WWTPs were available.

An assessment of the overall situation is conducted in conjunction with other indicators in the weekly report on acute respiratory diseases (ARE weekly report).

The course of the viral loads for influenza A and B virus, aggregated across all sites, is shown in Figure 1 in order to obtain an overall picture of the mean viral load and its development in Germany. Weekly mean values of the viral loads (given in gene copies / liter), previously transformed by the common logarithm, are computed, first for each site and then across all sites for the respective week. The estimation of the regression curve is weighted, so that weekly mean values with higher uncertainty are given a lower weight in the estimation and vice versa. The values of influenza A and B viruses have increased significantly in recent weeks, with higher values for influenza A than for influenza B. The development observed over the last few weeks may still change due to late notifications.

Figure 1: Aggregated viral loads for influenza A and influenza B viruses in wastewater over time along with regression curve (estimated using the LOESS method) and associated 95% confidence intervals. The change from the first to the second AMELAG phase, which was associated with a sharp decline in the number of participating treatment plants, is indicated by a vertical dashed line. The data was last updated on Tuesday the 11.02.2025, 10 am. The latest data used in the calculations is from the previous Wednesday’s sampling (05.02.2025, CW 6). Shown are 7-day averages, which refer to the period from Thursday to Wednesday; the most recent value is calculated from the data from 30.01.2025 (CW 5), to 05.02.2025 (CW 6). The date of the sample corresponds to the start date of the 24-hour composite sample.
The button on the right allows the display of the data points, regression curve and confidence intervals on the logarithmic scale or transformed back to the original scale. Changes in viral loads in the low value range are emphasized more strongly than values in the high value range on a logarithmic scale. By hovering over the individual points the calendar week, the date of the corresponding Wednesday, the viral load, the number of sites and the proportion of the total population that is included in the calculation at that time are shown.
Data for further sites are supplied subsequently.

The course of the viral load in wastewater is shown for the individual WWTPs in Figure 2.

Standort:

Figure 2: Viral loads for influenza A and influenza B viruses in wastewater over time (green and yellow points, respectively) along with the regression curves (green and yellow lines, estimated using the LOESS method, respectively) and corresponding 95% confidence intervals (light green and light yellow shaded areas). Measurements below the limit of quantification are shown as white points. The data was last updated on 11.02.2025, 10 am. The date of the sample corresponds to the start date of the 24-hour composite sample.
The location can be selected using the filter. The button on the right allows the display of the data points, regression curve and confidence intervals on the logarithmic scale or transformed back to the original scale. Changes in viral loads in the low value range are easier to recognize on a logarithmic scale. By hovering over the individual points the calendar week, date of sampling and viral load are shown.
If fewer than 10 data points are available in total, before a minimum 4-week time window with no data or before or after a change of laboratory, only the individual data points are shown. The corresponding regression curves and confidence intervals will be calculated when at least 10 data points are available.
Data from other sites are supplied subsequently.

Figure 3 shows the proportions of samples for influenza A and B viruses that are above or below the limit of quantification (LOQ).

Influenza A virus

Influenza B virus

Figure 3: Proportion of influenza A and B virus samples with measured viral loads above or below the LOQ. The numbers within the bars show the samples collected in the respective categories for the corresponding calendar week.

Some infectious agents or their components enter wastewater through feces, among other things. Specialized laboratories can process wastewater samples from wastewater treatment plants and detect the pathogens in them. This makes it possible to monitor the infection dynamics in the population connected to the respective treatment plant.

In the AMELAG project, SARS-CoV-2 and influenza viruses are monitored in wastewater. Nationwide, 168 wastewater treatment plants were participating by the end of 2024; up to 70 sites are expected to participate in 2025. In AMELAG, the German Environment Agency and the Robert Koch Institute are working together with health and environmental authorities of the federal states, laboratories and wastewater treatment plant operators. The project is funded by the Federal Ministry of Health.

The data shown in the report originate from the AMELAG project and from the ESI-CorA, COVIDready, Sars-GenASeq and Abwasser Biomarker CoV-2 projects. ESI-CorA was funded by the European Commission under the Emergency Support Instrument (ESI) (No 060701/2021/864650/SUB/ENV.C2). COVIDready, Sars-GenASeq and Wastewater Biomarker CoV-2 were funded by the German Federal Ministry of Education and Research (BMBF).

In the years 2022 to 2024, the following locations were funded by the federal state of Bavaria: Bayreuth, Erlangen, Nuremberg, Passau, Regensburg, Straubing and Weiden. In 2025, the following locations are funded by the federal sate of Bavaria: Altötting, Aschaffenburg, Bayreuth, Berchtesgaden, Erlangen, Freising, Hof, Ingolstadt, Neu-Ulm, Passau, Schweinfurt, Starnberg, Straubing, Weiden and Zusmarshausen. In 2025, the location of Wolfsburg is funded by the federal state of Lower Saxony.

The location of the wastewater treatment plants that have provided data so far in 2025 is shown in Figure 1. Older data from treatment plants that are no longer sampled are still shown in the report.

Figure 1: Map of wastewater treatment plants with data deliveries in 2025.

The methods for sampling, analytics, logistics, and data transmission and processing are described in four technical guidelines on http://www.rki.de/abwassersurveillance.

The data and software code of AMELAG are published on Zenodo and GitHub.

The exact procedures and potential use cases for wastewater surveillance are described in Epidemiological Bulletin 34/2024.

Limitations

Wastewater data do not allow conclusions to be drawn about disease severity or the burden on the healthcare system. Based on current knowledge, wastewater data cannot precisely determine incidence/prevalence or underreporting. For epidemiological assessments, wastewater data should always be considered in combination with other indicators, e.g. from syndromic surveillance.

Absolute viral loads cannot be directly compared to the number of infected individuals, especially over longer time periods, as the viral load excreted per infected person may vary, for example, between different virus variants. Likewise, absolute viral loads should not be compared between different sites and pathogens due to differences in sampling, laboratory techniques, normalization, and pathogen-specific differences.

The values obtained are influenced by a variety of factors (e.g., changes in wastewater inflow, heavy rainfall events, or tourist activities), which can only be partially compensated for through normalization of the data.

Suggested citation
Robert Koch-Institut, Umweltbundesamt: AMELAG-Weekly Report CW 07/2025 | DOI: 10.25646/13007

Wastewater Surveillance

Wastewater Surveillance

AMELAG Weekly Report 12.02.2025

Influenza A virus

Influenza B virus

AMELAG Weekly Report
12.02.2025